That means you agree that within 100 years there won't be any non-post-humans left. Everyone will be radically cybernetic at least, fully uploaded most likely. Intelligence will then be able to move in and out of all kinds of different substrates.

Now, remind me again why we'll need atmosphere then? Or big cities? Or gravity? Or to terraform anything? "We" (whatever that will mean once you can upload/download memories and share consciousness) are going to be sentient machines, whatever form those machines take - big boxes, rocket ships, anthropomorphic robots, nanobot clouds, or whatever else we feel like.

So if you subscribe to transhumanism, space colonization as Homo sapiens doesn't even make any sense, unless you think our civilization is going to be completely preoccupied with building zoos for Homo sapiens across the galaxy.

I honestly don't get the huge cognitive gap between space colonization and transhumanism. It's like otherwise perfectly intelligent futurists simply cannot hold these two ideas that they already subscribe to separately in their head at the same time.